 let lessons = [
  {
    title: "媒体查询响应式布局",
    click: 89,
    price: 12
  },
  {
    title: "FLEX 弹性盒模型",
    click: 45,
    price: 120
  },
  {
    title: "GRID 栅格系统",
    click: 19,
    price: 67
  },
  {
    title: "盒子模型详解",
    click: 29,
    price: 300
  }
];


function order(filed, type="asc") {
	return function(a, b) {
		return a[filed] - b[filed]
	}
}

function getColumn(filed) {
	return function(item, index, arr) {
		return item[filed]
	}
}

// console.log(lessons.sort(order('click')));
// 

 console.log(lessons.map(getColumn('title')));